Surface active polycarbodiimides and their dispersions

ABSTRACT

Disclosed are surface-active polycarbodiimides containing a hydrophilic portion and a hydrophobic portion joined through the reaction of a carbodiimide group with a reactive functional group. The surface-active polycarbodiimides may be linear or branched, monodisperse or polydisperse, but preferably are of the branched, monodispers type. The surface-active polycarbodiimides are useful as surfactants, and are particularly useful as emulsifiers in cross-linkable, carboxyl-containing resin systems, such as aqueous latexes.

This application is a division of prior U.S. application Ser. No.845,982, filed Mar. 31, 1986 now U.S. Pat. No. 4,820,863.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to surface-active difunctional andmultifunctional (i.e., with more than two carbodiimide groups)carbodiimides and their preparation and use as dispersing agents forpolycarbodiimides which are useful as cross-linking agents forcarboxyl-containing organic resins, preferably latex resins, orneutralized, carboxylated water-soluble resins, and carboxylatedsolution resins.

2. Summary of the Prior Art

Carbodiimides are a well-known class of organic compounds.Dicyclohexylcarbodiimide has been useful for many years as acondensation agent in the preparation of peptides, as described bySheelan and Hess (J. Chem. Soc., 77, 1067 (1955)). Monodisperse,difunctional carbodiimide compounds have been prepared by thedesulfurization of thioureas using hypochlorite. Such compounds wereprepared, for example, by Iwakura, et al. (Makromol. Chem., 98, 21(1966); Bull. Chem. Soc. Jpn., 40, 2383 (1967)). Multifunctional,linear, polydisperse polycarbodiimides have been prepared by Campbellfrom diisocyanatoalkanes or diisocyanatoarenes using a phospholine oxidecatalyst (U.S. Pat. No. 2,941,966 (1960)). Use of sodium hypochlorite todesulfurize thioureas to prepare multifunctional carbodiimides, i.e.,with more than two carbodiimide groups, is known but is reported to bevery difficult (Wagner, et al., Angew. Chem., 70, 819 (1981)). The artis summarized in Chem. Rev., 81, 589 (1981).

The use of polydisperse polycarbodiimides as cross-linkers forcarboxylated latex resins and neutralized carboxylated water-solublepolymers is known in the art. Specifically, co-assigned U.S. applicationSer. Nos. 691,378, filed Jan. 15, 1985 and 001,883, filed Jan. 9, 1987(the disclosure of which is incorporated herein by reference), teachesthe preparation of useful polycarbodiimides, useful as cross-linkers incarboxyl-containing resin systems, from certain mono-, di-, andtri-functional cycloaliphatic or saturated aliphatic isocyanates, inwhich the mono- and diisocyanates are optional, and co-assigned U.S.Pat. No. 4,487,964 discloses a method for the preparation of usefulpolycarbodiimide cross-linkers from mixed aromatic/aliphaticisocyanates. Of particular interest are the monodisperse,multifunctional carbodiimides disclosed in my co-pending, co-assignedU.S. patent application Ser. No. 747,190, filed June 21, 1985, whichwill be referred to in detail below.

The resin systems in which carbodiimide cross-linkers are particularlyuseful are those in which the material contains reactive carboxylgroups, such as are typically found in aqueous latexes used forcoatings. In the past, in order to prepare the cross-linkingcarbodiimide in compatible emulsion form, it has been necessary tosubject the carbodiimide to high-energy shear forces in the presence ofrelatively high concentrations of surfactants. Usually, this hasrequired the employment of special, high-shear mixing equipment, and hasexacted the further penalty of high energy costs. Since such emulsionsare often difficult to keep stabilized during storage, it has often beennecessary to avoid storage and shipment of the carbodiimide emulsionand, instead, to suffer the additional inconvenience of having to addemulsification equipment to the coating line.

The present invention effectively solves many of those problems of theprior art by providing polycarbodiimides which are relatively easy andinexpensive to emulsify, and in many cases, are virtuallyself-emulsifying. They are readily compatible with commercial,carboxyl-containing latexes, and are quite stable. In the event that itis considered convenient to utilize an emulsification step in-line, theemulsion may be effectively prepared using relatively simple mixingequipment, rather than expensive, high-shear devices.

According to the present invention there is provided a surface-activepolycarbodiimide of the formula

    R--X--R'                                                   (I)

wherein R is a residue of a hydrophobic organic compound containing atleast two carbodiimide groups; R' is a residue of an organic compoundhaving a hydrophilic segment and at least one functional group capableof reacting with a carbodiimide group; and X is a group formed by thereaction of a said carbodiimide group with a said functional group.

Likewise, there is provided a cross-linker emulsion comprising anadmixture, in aqueous medium, of (a) a hydrophobic polycarbodiimide, and(b) a polycarbodiimide of formula (I).

Similarly, there is provided a cross-linkable, carboxyl-containingemulsion (e.g., a latex) or a neutralized, carboxylated, water-solubleorganic resin, in combination with the cross-linker emulsion describedabove, as well as the cross-linked product thereof.

In addition, this invention provides methods for making thesurface-active polycarbodiimide of formula I, for making thecross-linker and cross-linkable emulsions, and for cross-linking suchemulsions by allowing volatilization of certain materials, to produce across-linked product.

As used herein, all defined groups are intended to include such groupscontaining any substitution which does not significantly interfere withthe use of the carbodiimides for their intended purpose. Likewise, allaromatic groups are intended to include fused aromatic rings as well assubstituted aromatic groups.

Also as used herein, the term "polycarbodiimide" is intended to includeboth monodisperse and polydisperse types of carbodiimides. The terms"multifunctional" and "polyfunctional," to the extent used, are usedinterchangeably and only in reference to monodisperse,polycarbodiimides.

DETAILED DESCRIPTION OF THE INVENTION

Incorporation of a carbodiimide cross-linker into formulationscontaining carboxylic, water-borne polymers requires either that thecross-linker be emulsified mechanically, or made surface-active for easydispersion. The emulsification step is cumbersome, and emulsifiedcarbodiimides are subject to a slow, unpreventable reaction with waterto form ureas, which limits their shelf-life. The present inventionpermits substantial simplification or elimination of the mechanicalemulsification step. This is achieved by use of a chemically modifiedcarbodiimide which is a surface-active species heretofore unknown to theart.

The surface-active carbodiimide of this invention can be prepared andused as a surfactant by adding it, with agitation, to solutions ofpolycarbodiimides, as with surfactants of the prior art. However, it isa surprising advantage of this invention that it permits the in situpreparation of dispersions of polycarbodiimides. That is, thepolycarbodiimide to be emulsified can be added directly to acarboxyl-containing medium, e.g., a latex, and the polycarbodiimide canthen be emulsified in the medium by addition, with stirring, of thesurface-active polycarbodiimide of this invention. The mild agitationroutinely supplied for mixing will ordinarily be adequate to effect thedispersion. However, if smaller droplet size is desired, shear can beincreased by use of more vigorous agitation. If very small droplets aredesired, any of the various homogenizing mixers known to the art can beemployed. In all cases, however, it will be found that thesurface-active carbodiimide of this invention produces dispersions morereadily for any given level of agitation than are available usingsurfactants of the prior art. It is to be understood that mixtures ofpolycarbodiimides can also be readily emulsified using this invention.If the surface-active carbodiimide is prepared in situ in a mixture ofpolycarbodiimides, it will be understood that surface-active specieswill be formed from each of the polycarbodiimide structures present,according to the reaction kinetics of each species.

The surface-active species of this invention is a polycarbodiimide resinconforming to the general formula (I): R--X--R', as described above. Intheory, R can be the residue of any hydrophobic organic group containingat least two carbodiimide linkages, one to form linkage X, and the otherto react with a carboxyl group of the resin to be cross-linked. Theadvantage of this latter reaction is that it binds the surface-activecomponent to the cross-linked resin matrix, thereby preventing migrationor "blushing" of the surfactant to the surface of a cross-linkedcoating. It is also possible, in fact, desirable, for R to contain morethan two carbodiimide groups, since the surfactant itself can thenparticipate in the cross-linking reaction.

In formula (I), R' can be the residue of any group having sufficienthydrophilicity to impart to the molecule the necessary surface-activecharacteristics. R' must, of course, be derived from a compound whichcontains, either initially or by modification, a group capable offorming linkage X by reaction with a carbodiimide group. It will beunderstood, of course, that if R' contains more than one such reactiongroup, such group should be chosen to be nonreactive or only relativelyslowly reactive with carbodiimide groups, so as to minimize anygellation or undesired cross-linking. As will be described more fullybelow, X may conveniently be the reaction product of a carbodiimide withan isocyanate. Various reactive species other than --NCO are, however,also useful. Such reactive species would include --COOH, carboxyl aminesalts, --SH, --OH, and --NH₂, as well as others known to the art. Itwill be understood by those skilled in the art that the reaction betweenan isocyanate and a carbodiimide is an equilibrium reaction; thus, itmay not ordinarily be possible to isolate the surface-activecarbodiimide so prepared. (However, in at least one system it has beenshown to be possible to isolate the carbodiimide/isocyanate dimer. SeeUlrich, et al., J. Am. Chem. Soc., 94, 3484 (1972)). If it is desired toutilize this reaction, it may be advisable to add theisocyanate-terminated surfactant to a high concentration ofcarbodiimide, since the reaction is then driven essentially tocompletion by "swamping" the isocyanate groups with carbodiimide groups.

As implied above, there are no inherent limitations on the structure ofR', other than the obvious facts that it should not be incompatible withcarbodiimide resins or carboxyl-containing emulsions. For ease ofpreparation, it will be apparent that various commercially availablenon-ionic surfactants are inherently reactive with carbodiimide groupsor can be modified to make them reactive with carbodiimide groups toform X. For example, poly(oxyalkylene)-based surfactants, such as thosepoly(ethylene oxide)-based surfactants available (from Union CarbideCorp.) under the trademark "Tergitol," contain free hydroxyl groupswhich can react with carbodiimide groups, or can be modified by reactionwith, e.g., a diisocyanate to provide a free isocyanate group to reactwith a carbodiimide group. A preferred hydroxyl-containing hydrophilicspecies comprises the poly(ethylene glycol) resins available (from UnionCarbide Corp.) under the trademark "Carbowax." Of these, thoseend-capped with a methoxy or ethoxy group are particularly preferred.Other hydroxy-containing hydrophilic species include poly(propyleneoxide) resins.

The reaction to form linkage X in formula (I) should be carried out inadvance of the use of the surface-active carbodiimide to form thecross-linker dispersion. The various reactions possible to form X willdepend, of course, upon the reactive groups selected, and will beperformed according to procedures well understood in the art.

The linkage X represents some general functional group formed throughany of the following cyclo-addition (1-2), addition (3-6), orcyclo-reversion (7) reactions. ##STR1##

The groups (X) formed from the above reactions (1-7) are the uretidinone(1), diazetidine thione (2), N-acyl urea (3), guanidine (4), isourea(5), isothiourea (6), and carbodiimide (7).

If it is necessary or desired to modify the surfactant R' by addition ofa carbodiimide-reactive group, that modification should be carried outin advance of the reaction to form linkage X. Again, the variousreactions possible to effect the modification will depend upon thereactive groups selected, and will be performed according to procedureswell understood in the art. In general, however, a nonionic surfactant,R', which is terminated with one of the reactive groups shown above isadded to a solution of the carbodiimide cross-linker under the necessaryconditions to ensure a reaction between the reactive groups attached tothe nonionic surfactant and the carbodiimide groups of themulti-functional carbodiimide.

As previously indicated, the surface-active carbodiimide of formula (I)can be effectively used in a variety of ways. It can be added to ahydrophobic carbodiimide, preferably in organic solvent solution, toform a surface-active material, which can then be added to across-linkable latex. The surface-active carbodiimide can alternativelybe formed in situ right in the hydrophobic carbodiimide solution itself.The surface-active carbodiimide also can be added to a mixture of latexand hydrophobic carbodiimide.

In preparing dispersions utilizing the surface-active carbodiimides ofthis invention, no particular precautions or unusual techniques arerequired. Procedures to be used are those familiar to the art. Ingeneral, however, it may be stated that materials should be added toeach other gradually, with moderate stirring and over a reasonable timeframe. It is usually preferable to add the oil phase to the water phase,i.e., add the surfactant solution to the latex. It is, however, possibleto add the water phase to the oil phase. This may, in fact, be desirablefor polydisperse polycarbodiimides (i.e., dispersity index D>1) since ittends to produce smaller droplet size for mixing energy expended. Adefoamer may be used, if desired, provided it is not incompatible withthe surface-active polycarbodiimide.

The concentration of the surface-active carbodiimide necessary to effectsatisfactory emulsification is not considered to be narrowly critical,and will be a matter of routine experimentation. Optimum concentrationcan be expected to depend to some extent, as with any othersurface-active material, upon the chemical structure of the material,e.g., the size and solubility of the hydrophilic moiety. As a generalguideline, however, the concentration of the surface-active carbodiimidecan be expected to be in the range of about 0.5 to about 10%, preferablyabout 0.5 to about 3%, most preferably about 1.5%, based upon the totalweight of the oil phase, i.e., polycarbodiimide plus solvent. Increasingthe surfactant concentration tends to decrease droplet size for anygiven hydrophile moiety. In addition, it should be kept in mind that ifthe surface-active carbodiimide is prepared from a resin having morethan two carbodiimide groups, the surface-active carbodiimide itselfwill participate in the ultimate cross-linking reaction; accordingly,the contribution of the surface-active carbodiimide should be taken intoaccount when considering the over-all concentration of cross-linkingemulsion.

It is also possible to utilize the surface-active carbodiimide of thisinvention in combination with other surfactants known to the art. Ifsuch supplemental surfactants are used, it is preferred that they be ofthe same ionic charge as any surfactants already present in the system(e.g., a latex) to which the surface-active carbodiimide is to be added,in order to minimize possible compatibility problems. However, thecombination of the nonionic surface-active carbodiimide of thisinvention with ionic types is also useful. Such combination might bedesirable when, for instance, emulsifying a polydispersepolycarbodiimide or a mixture of carbodiimides containing a polydispersetype. If a supplemental surfactant is used, it is preferable that it beof the anionic type, but should not, of course, contain chemicalmoieties which are reactive with carbodiimide functionality. Thus,surfactants containing reactive carboxyl groups, e.g., those based uponstearic or oleic acids, should be avoided. Preferred are thosesurfactants based upon sulfonic salts or upon sulfates. Theconcentration ratio of surface-active carbodiimide to supplementalsurfactant should be in the range of about 30/70 to about 70/30 byweight, preferably about 40/60 to about 60/40, most preferably about50/50. It will be understood that any ionic supplemental surfactant usedmust be selected to be compatible with any surfactant already present inthe carboxyl-containing material to be cross-linked. For example, manylatexes contain cationic surfactant residues, so should not be used withanionic supplemental surfactants.

Some other useful anionic surfactants are as follows:

    ______________________________________                                        Trade Name Chemical Name   Manufacturer                                       ______________________________________                                        Aerosol MA-BO                                                                            Sodium dihexyl  American Cyanamid                                             sulfosuccinate                                                     Akyposol DS-28L                                                                          Sodium Laurylether                                                                            Chem-Y                                                        sulfate                                                            Akyposol ALS-33                                                                          Ammonium Lauryl Chem-Y                                                        sulfate                                                            Akyposol NLS                                                                             Sodium Lauryl sulfate                                                                         Chem-Y                                             Akyposol TLS-42                                                                          Triethanolamine Lauryl                                                                        Chem-Y                                                        sulfate                                                            Alcoil 12S Sodium-ammonium Henkel Argentina                                              salts of alkyl aryl                                                           sulfonate                                                          Alcoil A550T                                                                             Triethanol amine salt of                                                                      Henkel Argentina                                              alkyl sulfonate                                                    Cycloryl 599                                                                             Sodium dodecylsulphate                                                                        Witco Chemical                                     Triton GR-5M                                                                             Dioctyl sodium  Rohm & Haas                                                   sulfosuccinate                                                     ______________________________________                                    

Some useful nonionic surfactants (hydroxyl-terminated) are listed below.

    ______________________________________                                        Trade Name                                                                              Chemical Name    Manufacturer                                       ______________________________________                                        Igepal Series                                                                           Alkylphenoxypoly GAF Corporation -                                            (ethylene oxy)ethanol                                                                          Chemical Products                                  Triton DN-14                                                                            Alkylpolyether alcohol                                                                         Rohm & Haas                                        Triton N-57                                                                             Nonylphenoxyl polyethoxy                                                                       Rohm & Haas                                                  ethanol (Tergitol Series)                                           Triton X-15                                                                             Octylphenoxypolyethoxy                                                                         Rohm & Haas                                                  ethanol                                                             Trycol OAL-23                                                                           Ethoxylated oleyl alcohol                                                                      Emery Industries                                   ______________________________________                                    

While probably not required for all possible systems within the scope ofthis invention, it is considered desirable and preferable to utilize acompatible solvent in the preparation of the surface-active carbodiimideand/or the cross-linker emulsion. There are no particular limitationsknown on the choice of a suitable solvent or combination of solvents,other than such solvent(s) should be non-reactive in the systems used.

Solvents for the surface-active carbodiimide and/or the cross-linkeremulsion include liquid compounds, or their combinations, which containester, ether, ketone, or alcohol functionality. Examples of suchsolvents include ethyl acetate, isopropyl acetate, butyl acetate. amylacetate, butyl phthalate, methyl CELLOSOLVE Acetate, CELLOSOLVE Acetate,Butyl CELLOSOLVE Acetate, CELLOSOLVE Acetate, Butyl CELLOSOLVE Acetate,CARBITOL Acetate, Butyl CARBITOL Acetate, glyceryl triacetate, hexyleneglycol diacetate, methyl ethyl ketone, diethyl ketone, methyl isobutylketone, ethyl butyl ketone, acetophenone, diisobutyl ketone, isophorone,cyclohexanone, isopropanol, isobutanol, 1-pentanol, 2-methyl pentanol,Methyl CELLOSOLVE, Butyl CELLOSOLVE, Hexyl CELLOSOLVE, Methyl CARBITOL,Propasol B, Propasol BEP, Propasol M, and phenyl glycol ether.

The primary purpose of the solvent is to solubilize the surfactant inthe presence of the cross-linker carbodiimide resin. If no solvent isused, a two-phase system is likely to result, since the cross-linkercarbodiimide resin is hydrophobic and the surface-active carbodiimideresin is, of course, hydrophilic. It will be understood, of course, thatthe more nearly hydrophilic the carbodiimide molecule is, the less theneed for a solvent. Thus, solvent use or concentration can be reducedwithin the scope of this invention by designing the surface-activecarbodiimide to contain ester groups or pendent hydroxyl groups, whichcan hydrogen-bond with water.

Modest agitation of the systems of this invention will produce dropletsizes in the range of about 0.4 to about 10 microns. As indicatedpreviously, this droplet size can be readily reduced by application ofsomewhat higher shear agitation, and/or increasing the level ofsurfactant in the oil phase. For use with latexes, it is desirable thatthe droplet size be in the range of about 0.4 to about 0.8 micron inorder to more nearly match the particle size typically found in latexes.In general, a longer hydrophilic chain in the surfactant portion of thesurface-active carbodiimide gives a more stable emulsion compared to ashorter chain at a given level of surfactant.

The carbodiimide cross-linker resin used may theoretically be anypolycarbodiimide resin known to the art and which is not incompatiblewith the carboxyl-containing, water-borne resin emulsion of thisinvention. Thus, for example, the cross-linker resin may potentially beselected from those taught by U.S. Pat. Nos. 3,929,733 and 3,972,933,which disclose linear aromatic polycarbodiimides, 2,853,473 whichdiscloses non-aromatic linear polycarbodiimides, and 4,487,964 whichdiscloses mixed aromatic/aliphatic linear polycarbodiimides.

Particularly preferred are those monodisperse, branched multifunctionalcarbodiimides disclosed in co-pending, co-assigned U.S. patentapplication Ser. No. 747,190, filed June 21, 1985, the disclosure ofwhich is incorporated herein by reference. Those resins conform to thegeneralized structure:

    M--[(R".sub.d NCN--R).sub.n ].sub.m --[(R".sub.d NCN--R').sub.p --Q].sub.q(II)

Wherein: M and Q may be the same or different and each represents theresidue of a compound adapted to function as a site for branching; R andR' may be the same or different and represent an alkyl (includingcycloalkyl) or aryl, radical or diradical which may be or contain cyano,nitro, halo, alkyl sulfide, dialkylaminoalkyl, substituted silane,alkoxy, and aryloxy moieties, and other substituted species of any ofthe foregoing; R" represents the same or different alkyl (includingcycloalkyl) or aryl diradical which may contain cyano, nitro, halo,alkyl sulfide, dialkylamino, substituted silane, alkoxy, and aryloxymoieties, and other substituted species of any of the foregoing.

More specifically, these carbodiimides comprise monodisperse, branched,multifunctional carbodiimides conforming to the structure: ##STR2##wherein: R¹, R², R³ and R⁴ may be the same or different and representorganic residues which do not substantially interfere with themultifunctional carbodiimide for its intended purpose; and D is anorganic residue.

Still more specifically, these carbodiimides comprise monodisperse,branched, multifunctional carbodiimides conforming to the structure:##STR3## wherein: R¹, R², and R⁴ may be the same or different andrepresent alkyl groups having 1 to about 12 carbon atoms; R⁵ and R⁶ maybe the same or different and represent hydrogen, alkyl (includingcycloalkyl), aryl, aralkyl, alkaryl, heterocyclic, cyano, nitro, halo,alkyl sulfide, dialkylaminoalkyl, silane, alkoxy, and aryloxy groups,and substituted species of any of the foregoing; Z is the residue of acompound adapted to function as a site for branching.

The moieties designated M, Q, D, and Z in the above formulas areintended to be quite broad and general in scope. It will be readilyappreciated from these formulas that by careful choice of startingmaterials and reaction sequence, all within the scope of this invention,it will be possible to prepare complex molecular structures.Accordingly, it is to be understood that M, Q, D, and Z are intended toinclude all structures which do not significantly impair the use of thebranched multifunctional carbodiimides for their intended purpose.

Selection of optimum molecular weight for the cross-linker carbodiimidewill be a matter of experimentally balancing, for example, suchvariables as the degree of branching, the distance between carbodiimidemoieties, backbone chain length, and the compatibility of thepolycarbiimide with the cross-linkable resin. As a general guideline,referring to formulas I, II and III, the ranges for the subscriptletters are:

n=0 to ˜6, preferably 1 to ˜2;

m=3 to ˜5, preferably 3 to ˜4;

p=1 to ˜6, preferably 1 to ˜2;

q=0 to ˜4, preferably 0 to ˜3;

r=1 to ˜6, preferably 1 to ˜4;

s=1 to ˜6, preferably 1 to ˜4;

t=1 to ˜6, preferably 1 to ˜4;

x=1 to ˜6, preferably 1 to ˜4;

y=1 to ˜6, preferably 1 to ˜4;

z=1 to ˜6, preferably 1 to ˜4;

a=0 to ˜12, preferably 1 to ˜2;

b=0 to ˜12, preferably 3 to ˜4;

c=0 to ˜12, preferably 2 to ˜3;

d=0 to ˜12, preferably 1 to ˜4;

The above tabulation is offered with the observations that m must be atleast 3 for branching to occur, and that d may be different in differentbranches.

Another preferred group of polycarbodiimides are those disclosed inco-pending, co-assigned U.S. patent application Ser. No. 691,378, filedJan. 15, 1985, the disclosure of which is incorporated herein byreference. These materials comprise polydisperse, linear, polyfunctionalpolycarbodiimides derived from the reaction of mono-, di-, andtri-cycloaliphatic or saturated aliphatic isocyanates wherein thecycloaliphatic moieties contain from 5 to about 7 carbons and can besubstituted with alkyl having 1 to about 6 carbons, and oxygen, and thesaturated aliphatic moieties contain from 1 to about 18 carbons, whereinthe mono- and triisocyanates are optional.

Such polycarbodiimides can be prepared in a variety of ways. In apreferred synthesis, the polycarbodiimides are prepared by reaction ofmono-, di-, and optionally tri-isocyanates, with the easiest structuresto conceptualize being based on mono- and diisocyanates in the molarratio of about 2:1 to about 2:10 to yield the carbodiimide, withevolution of carbon dioxide, by the following general equation:

    2R--NCO→R--NCN--R+CO.sub.2

This process usually requires a catalyst, and a preferred catalyst is3-methyl-1-phenyl-2-phospholene-1-oxide (which may be abbreviated"MPPO"), having the formula: ##STR4## wherein: M and Q are independentlythe residue of a compound adapted to function as a site for branching;

R¹, R², R⁴, R⁵, R⁶ and R⁷ are independently divalent organic radicals;

R³ and R⁸ are independently monovalent organic radicals;

a is an integer having a value from 3 to about 6 corresponding to thevalency of M;

b is an integer having a value from 0 to about 4;

c is an integer having a value of 0 or 1;

d is an integer having a value of 0 or 1;

e is an integer having a value of from 0 to about 4;

f is an integer having a value from 0 to about 4; and

g is an integer having a value from 0 to about 4;

h is an integer having a value of 0 or 1, wherein for each value of a,R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, b, c, d, e, f, g and h may be the sameor different, with the provisos that:

(i) for each a, the sum of c+d is 1;

(ii) for each a wherein d is 0, e, f, g, and h all have a value of 0;and

(iii) for each a wherein d is 1, h is 1.

As represented by Formula I, R¹, R², R⁴, R⁵, R⁶ and R⁷ are independentlysubstituted or unsubstituted alkyl (including cycloalkyl) or arylradicals, wherein such substituted alkyl and aryl radicals includeradicals having substituents selected from the group consisting ofcyano, nitro, halo, alkylthio, dialkylaminoalkyl, alkylsilyl, alkoxy,and aryloxy moieties, and the like. As represented by Formula I, R³ andR⁸ are independently substituted or unsubstituted alkylene or aryleneradicals, wherein such substituted alkylene and arylene radicals includeradicals having substituents selected from the group consisting ofcyano, nitro, halo, alkylthio, dialkylaminoalkyl, alkylsilyl, alkoxy,and aryloxy moieties, and the like. ##STR5##

It is not necessary to use a triisocyanate. A combination of mono- anddiisocyanates in a molar ratio of about 2:2 to about 2:4 is preferred.

The reaction is preferably accomplished in non-reactive solvents, suchas, aromatic hydrocarbons having 6 to about 12 carbons, aliphatic estersor glycol diesters, amyl acetate, butyl acetate, propyl propionate,ethyl butyrate, xylene, toluene, diethyl benzene, benzene, diethyleneglycolether diacetate, dipropylene glycol ether dibutyrate and hexyleneglycol diacetate. The reaction mixture is stirred vigorously, and asmall amount of nitrogen is sparged in to assist in driving the reactionto completion by removal of carbon dioxide. Generally, mixtures ofisocyanates are employed, with the relative molar proportions of mono-,di- and triisocyanates adjusted to yield the desired product.

In a typical preparation, two moles of butyl isocyanate are reacted withthree moles of isophorone diisocyanate to yield an oligomericpolycarbodiimide having approximately four moles of carbodiimidefunctionality, barring any side reactions. These reactants are chargedto approximately 50% by weight of reactant in amyl acetate along withabout 0.3% by weight of the catalyst. The mixture would be continuouslysparged with a small amount of nitrogen and stirred vigorously whileheated to approximately 140° C. and held until complete conversion ofthe isocyanate to the carbodiimide is observed in the infrared spectrum.

This structure may be made surface-active, according to the invention,through the chemical reactions shown in FIG. 1. These are the chemicalreactions occurring, in Examples 1, 3, and 5, below.

Use of this synthesis regime typically results in a broad molecularweight range of about 100 to about 80,000 in the polycarbodiimideproduct. For a typical product, the number average molecular weight(M_(n)), determined by vapor phase osmometry, would be approximately795, and the weight average molecular weight (M_(w)), determined byRayliegh light scattering, would be approximately 2227. This produces adispersity index, D=M_(w) /M_(n), of 2.8.

Many variations on this synthesis regime will be apparent to one skilledin the art.

While the saturated aliphatic isocyanates previously listed include themore widely available commercial materials, many others can be used asexemplified by:

1,4-tetramethylene diisocyanate

1,12-dodecane diisocyanate

cyclobutane-1.3-diisocyanate

cyclohexane-1.3-diisocyanate

cyclohexane-1.4-diisocyanate

hexahydrotolylene-2,4- and

-2,6-diisocyanate.

While the solvents previously listed are preferred, many other solventswould be suitable. Requirements for suitable solvents include having asufficiently high boiling point to allow efficient accomplishment of thedesired reaction and that the solvent not contain active hydrogenfunctionality such as would react with the isocyanate starting materialor the carbodiimide product. Examplary solvents include:ethylbutylketone, acetophenone, propriophenone, diisobutylketone,cyclohexanone, decalin, methyl CELLOSOLVE acetate, CELLOSOLVE acetate,butyl CELLOSOLVE acetate, CARBITOL acetate, butyl CARBITOL acetate, andglycoldiacetate.

Many variations of the catalyst are employable. Examples include thenon-oxidized phospholene compound as well as the phospholene sulfide.Additional alternatives include substitutions on and for the phenylgroup attached to the phosphorous atom, such as by the ethyl moiety.Additional substitutions on the phosphorous ring can be made, as forexample: hydrogen, alkenyl, aryl, aralkyl, alkoxy, chlorine, andbromine.

The process need not be operated at 140° C. for acceptable product hasalso been produced at 130° C. to 160° C. Operation below 120° C. mayyield unacceptably long cycle times, while operation at 160° C. or abovemay yield undesired quantities of by-product.

The following examples illustrate various embodiments of the invention,but do not limit it in any way. All concentrations are by weight. Theanionic surfactants used in these examples are as follows:

    ______________________________________                                        Trade Name      Chemical Name                                                 ______________________________________                                        Aerosol OT-75   Dioctyl ester of sodium                                                       sulfosuccinic acid                                            Aerosol TR-70   Bis(tridecyl)ester of sodium                                                  sulfosuccinic acid                                            Aerosol AY-65   Diamyl ester of sodium                                                        sulfosucconic acid                                            ______________________________________                                    

All the above are manufactured by American Cyanamid.

Referring to the chemical reactions written previously, the average nfor the MPEG's used is as follows: MPEG 750: n=17; MPEG 3000: n=68; MPEG5000: n=114. In general it may be said that n may range from about 10 toabout 150, preferably from about 15 to about 120.

The examples which follow illustrate the invention in various usefulembodiments, but are not intended to limit the invention in any way.

EXAMPLES EXAMPLE 1 Preparation of Surface-Active α/ω-Dibutylpoly(isophorone carbodiimide) Using CARBOWAX® Methoxypolyethylene glycol(MPEG) 5000 as Hydrophile

Into a 2000-ml resin kettle equipped with a heating mantle, mechanicalstirrer, thermometer, and nitrogen purge were charged 486.50 g of amylacetate, 420.15 g isophorone diisocyanate and 20.5 g Carbowax MPEG 5000.The solution was heated, with stirring, to 70° C., then 0.50 g ofbismuth III octanoate (25% active in mineral oil) was added. After 30minutes, 124.81 g of butyl isocyanate and 33 g of a 10% solution byweight of 3-methyl-1-phenyl-2-phospholene-1-oxide in xylene werecharged. The solution was heated, with stirring, at 140° C. for 19hours, then the solids adjusted to 43% by the addition of 128.93 g ofamyl acetate. The product was cooled and packaged (1055.2 g). Theinfrared spectrum of the surface-active polycarbodiimide showedelimination of the isocyanate peak (2260 cm⁻¹) with formation of thecarbodiimide peak (2130 cm⁻¹).

EXAMPLE 2 Dispersion of Product of Example 1 in Water

To 42.21 g of a water solution (2.08% triethylamine, by weight) wereadded 57.61 g of the surface-active polycarbodiimide from example 1,while stirring with a 3-blade impeller. After the addition of thepolycarbodiimide, the mixture was stirred for 3 minutes with a 3-bladeimpeller, then the emulsion was homogenized for 3 minutes with a VirTushomogenizer. Analysis showed the droplet size to be about 1.44 microns.

EXAMPLE 3 Preparation of Surface-Active α/ω-Dibutyl poly(isophoronecarbodiimide) using CARBOWAX® Methoxypolyethylene glycol 3000 asHydrophile

The procedure was similar to that described in Example 1 except thatCarbowax MPEG 3000 was substituted for Carbowax MPEG 5000.

EXAMPLE 4 Dispersion of the Product of Example 3 in Water

The surface-active polycarbodiimide described in Example 3 wasemulsified using the procedure described in Example 2. Analysis showedthe droplet size to be about 1.82 microns.

EXAMPLE 5 Preparation of Surface-Active α/ω-Dibutyl poly(isophoronecarbodiimide) using CARBOWAX® Methoxypolyethylene glycol 750 asHydrophile

The procedure was similar to that described in Example 1 except thatCarbowax MPEG 750 was substituted for Carbowax MPEG 5000.

EXAMPLE 6 Dispersion of Product of Example 5 in Water

The surface-active polycarbodiimide described in Example 5 wasemulsified using the procedure described in Example 2. Analysis showedthe droplet size to be about 13.24 microns.

EXAMPLE 7 Evaluation of the Products of Examples 1, 3, and 5 in thePresence of Anionic Surfactants

The nonionic surface-active polycarbodiimides of examples 1, 3, and 5were evaluated in combination with various anionic surfactants. Thedesired nonionic surfactant levels were obtained by blending anα/ω-dibutyl poly(isophorone carbodiimide) which was not surface-activeto the polycarbodiimides of Examples 1, 3, or 5. The procedure isgeneral, and is as follows:

An oil phase and a water phase are prepared to have the followingcompositions:

    ______________________________________                                                         Solids, %                                                                            Mass (g)                                              ______________________________________                                        Oil Phase                                                                     Example l          43.0     26.65                                             α,ω-dibutyl poly(isophorone                                                          49.2     30.96                                             carbodiimide)                                                                 Foamaster VF       --       0.28                                              Water Phase                                                                   Water                       41.33                                             Triethylamine               0.88                                              ______________________________________                                    

The oil phase is added to the water phase while stirring with a 3-bladeimpeller. The emulsion which forms is then homogenized for 3 minuteswith a VirTus homogenizer. The solids level of the emulsion is 26.7%.

Using the above procedure, a series of samples was prepared as shown inTable I. In this table, all anionic surfactants are sulfonated soapsavailable from American Cyanamid. In order of increasing hydrophobicity,AY<AOT<TR.

                  TABLE I                                                         ______________________________________                                                      Mol.            Anionic/ Percent                                Sam- Ex-      Wt.     Anionic Nonionic Total                                  ple  amples   MPEG    Surfactant                                                                            Surfactant                                                                             Surfactant                             ______________________________________                                        1    1        5000    AY-65   40/60    1.5                                    2    1        5000    AOT-75  50/50    3.0                                    3    1        5000    TR-70   60/40    2.25                                   4    2        3000    AY-65   50/50    2.25                                   5    2        3000    AOT-75  60/40    1.5                                    6    2        3000    TR-70   40/60    3.0                                    7    3         750    AY-65   60/40    3.0                                    8    3         750    AOT-75  40/60    2.25                                   9    3         750    TR-70   50/50    1.5                                    ______________________________________                                    

Evaluations of Samples 1-9 are shown in Table II.

                  TABLE II                                                        ______________________________________                                                      Brook-                                                                Drop-   field                Number of                                        let     Viscos-  Appearance of                                                                             Freeze-Thaw                                      Size    ity at   Emulsion After                                                                            Cycles Before                                    (Mi-    60 RPM   48 hours                                                                             18 days                                                                              Appearance                               Trials                                                                              crons)  (cps)    at 47° C.                                                                     at 25° C.                                                                     of Oil Phase                             ______________________________________                                        1     1.05    2900     No     No     >4                                                              change change                                          2     0.49    5600     No     No     >4                                                              change change                                          3     0.64    3500     No     No     >4                                                              change change                                          4     0.63    787      No     No     >4                                                              change change                                          5     0.68    86       No     No     >4                                                              change change                                          6     0.58    125      No     No     >4                                                              change change                                          7     9.29    76       Oil sepa-                                                                            Oil sepa-                                                                             0                                                              ration ration                                          8     0.54    85       Oil sepa-                                                                            Oil sepa-                                                                             0                                                              ration ration                                          9     0.66    65       Oil sepa-                                                                            Oil sepa-                                                                             0                                                              ration ration                                          ______________________________________                                    

EXAMPLE 8 Preparation of a Water-dispersible Carbodiimide using CARBOWAXMethoxypolyethylene glycol 750 as Hydrophile

To a 3-neck, 500 ml round bottom flask equipped with a mechanicalstirrer and thermometer were charged 200 g of amyl acetate, 20.0 g(0.0900 mole) of isophorone diisocyanate, 40.0 g (0.0533 mole) ofCARBOWAX methoxypolyethylene glycol 750, and 0.5 g of bismuth IIIoctanoate (25% active in mineral oil). The contents of the flask wereheated at 100° C. for 2 hours. The flask was then cooled and the crudeisocyanate-terminated CARBOWAX methoxypolyethylene glycol precipitatedby adding the contents of the flask to 500 ml of hexane. The product waswashed 3 times with 50 ml portions of hexane, then dried overnight in avacuum oven. The infrared spectrum of the material showed an isocyanateband (2240 cm⁻¹). The yield was 87.5%.

To prepare the "surface-active" carbodiimide, 7 g of1,3,6-tri(N-isopropyl-N'-methylene carbodiimide) hexane (prepared by thebromotriphenyl phosphine bromide process (see Example 12), then made47.8% active in amyl acetate) and 0.105 g of the aboveisocyanate-terminated CARBOWAX methoxypolyethylene glycol were heated ina small vial to 50° C. to form a homogeneous solution, then cooled toroom temperature. After 24 hours, an infrared spectrum of the abovematerial showed no detectable isocyanate band.

The dispersibility and reactivity of the above carbodiimide wereevaluated in the formulation described below.

    ______________________________________                                        UCAR 4620 (46.33% solids)                                                                         100.91 g                                                  Dimethylethanolamine                                                                              0.40 g                                                    in water (50%)                                                                Butyl CELLOSOLVE    7.48 g                                                    Water               7.48 g                                                    ______________________________________                                    

While rapidly stirring the above partial formulation with a 3-bladeimpeller, 3.05 g (3 PHR) of the chemically modified carbodiimidedescribed above were added and stirring continued for 5 minutes.Evaluations of the above formulation are shown in Table I.

                  TABLE I                                                         ______________________________________                                                                          Percent                                     Oven                 Methyl Ethyl Carbodiimide                                Temperature Time     Ketone       Remaining                                   °F.  (minutes)                                                                              Double Rubs  in Polymer                                  ______________________________________                                        140         15         71         28.0                                        185         5         167         25.6                                        200         5        +300         20.5                                        220         5        +300         19.2                                        260         15       +300          0.1                                        ______________________________________                                         Notes:                                                                        a. Formulation: UCAR 4620, Butyl CELLOSOLVE, 6 PHR; Base,                     Dimethylethanolamine; pH, 8.4; Crosslinker, surfaceactive form of             1,3,6tri(N-isopropyl-Nmethylene carbodiimide) hexane, 3 PHR.                  b. The 1,3,6tri(N-isopropyl-Nmethylene carbodiimide) hexane was prepared      by dehydration of the corresponding urea using bromotriphenylphosphine        bromide; % NCN of theory was 84%.                                             c. The 1,3,6tri(N-isopropyl-Nmethylene carbodiimide) hexane was chemicall     modified with 1% of an isocyanateterminated CARBOWAX methoxy polyethylene     glycol with an average molecular weight of 972 g/mole.                        d. The percent of carbodiimide remaining unreacted in the coating was         determined by FTIR ATR.                                                       e. Wet films of the formulation were drawn down on Leneta paper using a       #60 wirewound rod, then cured in a forced air oven. The thickness of the      dried coating was 1.2 ± 0.2 mils.                                     

EXAMPLE 9 Preparation of a Water-dispersible Carbodiimide Prepared froma Trifunctional Carbodiimide

To a 3-neck, 500 ml round bottom flask equipped with a mechanicalstirrer and thermometer were charged 200 g of amyl acetate, 20.0 g(0.0900 mole) of isophorone diisocyanate, 10.0 g (0.00200 mole) ofCARBOWAX methoxypolyethylene glycol 5000, and 0.5 g of bismuth IIIoctanoate (25% active in mineral oil). The contents of the flask wereheated at 100° C. for 2 hours. The flask was then cooled and the crudeisocyanate-terminated CARBOWAX methoxypolyethylene glycol precipitatedby adding the contents of the flask to 500 ml of hexane. The product waswashed with 50 ml of hexane, then dried in a vacuum oven at 25° C. toconstant weight. The yield of the product was 100%.

To prepare the "surface-active" carbodiimide, 7.0 g of1,3,6-tri(N-isopropyl-N'-methylene carbodiimide) hexane (prepared by thephosphine bromide process then made 47.8% active in amyl acetate) and0.105 g of the above isocyanate-terminated CARBOWAX methoxypolyethyleneglycol were heated in a small vial to 70° C., then cooled to roomtemperature.

The dispersibility and reactivity of the above carbodiimide wereevaluated in the formulation described below.

    ______________________________________                                        UCAR 4620 (46.33% solids)                                                                         100.91 g                                                  Dimethylethanolamine                                                                              0.40 g                                                    in water (50%)                                                                Butyl CELLOSOLVE    7.48 g                                                    Water               7.48 g                                                    ______________________________________                                    

While rapidly stirring the above partial formulation with a 3-bladeimpeller, 3.05 g (3 PHR) of the chemically modified carbodiimidedescribed above were added and stirring continued for 5 minutes.Evaluations of the above formulation are shown in Table II.

                  TABLE II                                                        ______________________________________                                                                          Percent                                     Oven                 Methyl Ethyl Carbodiimide                                Temperature Time     Ketone       Remaining                                   °F.  (minutes)                                                                              Double Rubs  in Polymer                                  ______________________________________                                        140         15         91         25.7                                        185         5         209         22.6                                        200         5        +300         19.3                                        220         5        +300         17.6                                        260         5        +300          1.1                                        ______________________________________                                         Notes:                                                                        a. Formulation: UCAR 4620, Butyl CELLOSOLVE, PHR; Base,                       Dimethylethanolamine; pH, 8.4; Crosslinker, surfaceactive form of             1,3,6tri(N-isopropyl-Nmethylene carbodiimide)hexane, 3 PHR.                   b. The 1,3,6tri(N-isopropyl-Nmethylene carbodiimide) hexane was prepared      using the bromotriphenylphosphine bromide process; percent NCN of theory      of 84%.                                                                       c. The 1,3,6tri(N-isopropyl-Nmethylene carbodiimide) hexane was chemicall     modified with 1% of an isocyanateterminated CARBOWAX methoxy polyethylene     glycol with an average molecular weight of 5222 g/mole.                       d. The percent of carbodiimide remaining unreacted in the coating was         determined by FTIR ATR.                                                       e. Wet films of the formulation were drawn down on Leneta paper using a       #60 wirewound rod, then cured in a forced air oven. The thickness of the      dried coating was 1.2 ± 0.2 mils.                                     

EXAMPLE 10 Preparation of a Water-Dispersible Carbodiimide

To prepare the "surface-active" carbodiimide, 14.0 g of1,3,6-tri(N-cyclohexyl-N'-methylene carbodiimide) hexane (prepared bythe hypochlorite process (see Example 13), then made 47.8% active inamyl acetate) and 0.211 g of an isocyanate-terminated CARBOWAXmethoxypolyethylene glycol (average molecular weight, 972 g/mole, wereheated in a small vial to 50° C. to obtain a homogeneous solution (<2hours), then the solution was allowed to cool. An infrared spectrum ofthe above material showed no detectable isocyanate band.

The dispersibility and reactivity of the "surface-active"1,3,6-tri(N-cyclohexyl-N'-methylene carbodiimide) hexane were evaluatedin the formulation described below:

    ______________________________________                                        UCAR 4431 (42.3% solids)                                                                         55.36 g                                                    Dimethylethanolamine                                                                             0.30 g                                                     in water (50%)                                                                Butyl CELLOSOLVE   3.74 g                                                     Water              3.74 g                                                     ______________________________________                                    

While rapidly stirring the above partial formulation with a 3-bladeimpeller, 1.98 g (4 PHR) of the chemically modified carbodiimidedescribed above were added and then stirring continued for 5 minutes.Evaluations of the above formulation are shown in Table III.

                  TABLE III                                                       ______________________________________                                        Oven                                                                          Temperature  Time     Methyl Ethyl Ketone                                     °F.   (minutes)                                                                              Double Rubs                                             ______________________________________                                        140          2         73                                                     140          15       126                                                     185          5        185                                                     200          5        182                                                     260          15       +300                                                    ______________________________________                                         Notes:                                                                        a. Formulation: UCAR 4431; Butyl CELLOSOLVE, 15.9 PHR; Base,                  Dimethylethanolamine, 0.63 PHR; pH, 8.13; Crosslinker, surfaceactive form     of 1,3,6tri(N-cyclohexyl-Nmethylene carbodiimide) hexane, 4 PHR.              b. Crosslinker was prepared by the hypochlorite process; percent NCN of       theory was 73.7%.                                                             c. The 1,3,6tri(N-cyclohexyl-Nmethylene carbodiimide) hexane was              chemically modified with 1% of an isocyanateterminated CARBOWAX               methoxypolyethylene glycol with an average molecular weight of 972 g/mole     d. Wet films of the formulation were drawn down on Leneta paper using a       #60 wirewound rod, then cured in a forced air oven. The thickness of the      dried coating was 1.2 ± 0.2 mils.                                     

EXAMPLE 11 Preparation of a Water-dispersible Carbodiimide

To prepare the "surface-active" carbodiimide of higher surfactant level,14.0 g of 1,3,6-tri(N-cyclohexyl-N'-methylene carbodiimide) hexane(prepared by the hypochlorite process, then made 47.8% active in amylacetate) and 1.02 g of an isocyanate-terminated CARBOWAXmethoxypolyethylene glycol (average molecular weight, 972 g/mole) wereheated in a small vial to 50° C. to obtain a homogeneous solution (<2hours), then the solution was allowed to cool.

The dispersibility and reactivity of the "surface-active"1,3,6-tri(N-cyclohexyl-N'-methylene carbodiimide) hexane were evaluatedin the formulation described below.

    ______________________________________                                        UCAR 4431 (42.3% solids)                                                                         55.36 g                                                    Dimethylethanolamine                                                                             0.30 g                                                     in water (50%)                                                                Butyl CELLOSOLVE   3.74 g                                                     Water              3.74 g                                                     ______________________________________                                    

While rapidly stirring the above partial formulation with a 3-bladeimpeller, 2.11 g (4 PHR) of the chemically-modified carbodiimidedescribed above were added. The stirring was continued for 5 minutes.Evaluations of the above formulation are shown in Table IV.

                  TABLE IV                                                        ______________________________________                                        Oven                                                                          Temperature  Time     Methyl Ethyl Ketone                                     °F.   (minutes)                                                                              Double Rubs                                             ______________________________________                                        140          2         101                                                    185          5         300                                                    200          5        +300                                                    260          15       +300                                                    ______________________________________                                         Notes:                                                                        a. Formulation: UCAR 4431; Butyl CELLOSOLVE, 15.9 PHR; Base,                  Dimethylethanolamine, 0.63 PHR; pH, 8.02; Crosslinker, surfaceactive form     of 1,3,6tri(N-cyclohexyl-Nmethylene carbodiimide)hexane, 4 PHR.               b. Crosslinker was prepared by the hypochlorite process; percent NCN of       theory was 73.7%.                                                             c. The 1,3,6tri(N-cyclohexyl-Nmethylene carbodiimide) hexane was              chemically modified with 7% of an isocyanateterminated CARBOWAX               methoxypolyethylene glycol with an average molecular weight of 972 g/mole     d. Wet films of the formulation were drawn down on Leneta paper using a       #60 wirewound rod, then cured in a forced air oven. The thickness of the      dried coating was 1.2 ± 0.2 mils.                                     

EXAMPLE 12 Preparation of 1,3,6-tri(N-isopropyl-N'-methylenecarbodiimide) hexane

Into a 3-neck, 5000 ml, round-bottom flask equipped with a thermometer,mechanical stirrer, and pressure-equalizing dropping funnel were charged484.59 g (1.847 moles of triphenylphosphine and 2585 ml of driedmethylene chloride. The contents of the flask were cooled to 1° C., then295.2 g (1.847 moles) of bromine dissolved in 200 ml of methylenechloride were dropped into the stirred triphenylphosphine solution overa 1.73-hour period while maintaining the temperature of the contents ofthe flask between 1° and 6° C. After the addition of the brominesolution, 377.7 g (3.733 moles) of triethylamine were added to thebromotriphenylphosphine bromide solution over a 1.3-hour period whilemaintaining the temperature between 0° and 1° C.

To prepare the multifunctionalcarbodiimide, 220.0 g (0.5132 mole) of1,3,6-tri(N-isopropyl-N'-methylene urea) hexane were added portionwiseto the stirred solution of bromotriphenylphosphine bromide solution overa 1-hour period while maintaining the temperature of the contents in theflask between 0° and 2° C. After the addition of the urea, the contentsof the flask were stirred for 1.75 hours.

After the reaction period, triphenylphosphine oxide and triethylhydrogen bromide were filtered from the methylene chloride solutioncontaining the carbodiimide. The solution containing the multifunctionalcarbodismide was then washed with 4175 g of cold water. Thepolycarbodiimide solution was then dried overnight over 4 Å molecularsieves.

The methylene chloride was then removed using a roto-evaporator at 38°C. (345 mm Hg). The vacuum was gradually increased to 5 mm Hg. The1,3,6-tri(N-isopropyl-N'-methylene carbodiimide) hexane was thenextracted from the triphenylphosphine oxide residue with four 1400 mlportions of hexane. The extracts were filtered, then combined to form aclear solution of the multifunctional carbodiimide in hexane. The hexanewas removed using a roto-evaporator at 38° C. (115 mm Hg) until 350 mlof solution remained. The solution was refiltered, and most of theremaining hexane removed using a roto-evaporator at 38° C. (7 mm Hg).

The infrared spectrum of the clear amber oil showed a large carbodiimideband (2130 cm⁻¹). The carbodiimide solution, which was 94.2% active inhexane, had a Brookfield viscosity of 14 cps (LVT #1 spindle at 60 rpm).The equivalent Gardner Bubble viscosity was 0.144 Stoke. The yield ofthe carbodiimide was 80.3%. Titration of an aliquot by the procedure ofZarembo and Watts (Microchem. J. Symp. Ser., 2, 591 (1962) yielded acarbodiimide functionality of 26.8% (theory 32.0%). The theoreticalfunctionality of the material was 3.

EXAMPLE 13 Preparation of 1,3,6-tri(N-cyclohexyl-N'-methylenecarbodiimide) hexane from a Trifunctional Thiourea) by the HypochloriteProcess

Into a 3-neck, 500 ml round bottom flask equipped with a thermometer,bubbler, and mechanical stirrer were charged 3665 ml of water and 426.99g (10.676 moles) of sodium hydroxide. The basic water solution wascooled to -5° C., then 257.91 g (3.628 moles) of chlorine were bubbledinto the basic water solution while maintaining the temperature between-3° and -5° C.

To prepare the carbodiimide, 173.92 g (0.2913 moles) of1,3,6-tri(N-cyclohexyl-N'-methylene thiourea) hexane in 376.55 g ofmethylene chloride were added to the stirred hypochlorite solution overa 3-minute period. After the addition of the thiourea, the reaction wasrun for 4 hours while maintaining the temperature between 5° and 8° C.The contents of the reactor were then cooled to -5° C., then the organicphase separated from the water layer. The organic phase was filtered toremove residual sulfur, washed with 100 ml of water, then driedovernight over a bed of 4 Å molecular sieves.

After drying, the organic phase was refiltered, and the methylenechloride removed using a roto-evaporator at 38° C. (345 mm Hg). Duringthe removal of the methylene chloride, the temperature was graduallyincreased over a 2-hour period to 50° C. (7 mm Hg). The infraredspectrum of the amber oil showed a large carbodiimide band (2130 cm⁻¹).The carbodiimide solution was 90.3% active carbodiimide in methylenechloride. The yield of carbodiimide was 69.1%. Titration of an aliquotby the procedure of Zarembo and Watts yielded a percent carbodiimidefunctionality of 18.8% (theory 25.5%). The theoretical functionality ofthe material was 3.

I claim:
 1. A carboxyl-reactive surface-active polycarbodiimide of theformula

    R--X--R'

wherein R is a residue of a hydrophobic organic compound containing atleast two carbodiimide groups; R' is a residue of an organic compoundhaving a hydrophilic segment and at least one functional group capableof reacting with a carbodiimide group; and X is a group formed by thereaction of a said carbodiimide group with a said functional group.
 2. Asurface-active polycarbodiimide of claim 1 wherein X is selected fromthe group consisting of uretidinone, diazetidine thione, N-acyl urea,guanidine, isourea, isothiourea, and carbodiimide.
 3. A surface-activepolycarbodiimide of claim 1 wherein R is a residue of a monodisperse,branched polycarbodiimide.
 4. A carboxyl-reactive surface-activepolycarbodiimide of claim 3 wherein the monodisperse, branchedpolycarbodiimide has the generalized structure:

    M--[(R".sub.d NCN--R).sub.n ].sub.m --[(R".sub.d NCN--R').sub.p --Q].sub.q

wherein: M and Q may be the same or different and each represents theresidue of a compound adapted to function as a site for branching; R andR' may be the same or different and represent an alkyl (includingcycloalkyl) or aryl, radical or diradical which may be or contain cyano,nitro, halo, alkyl sulfide, dialkylaminoalkyl, substituted silane,alkoxy, and aryloxy moieties, and other substituted species of any ofthe foregoing; R" represents the same or different alkyl (includingcycloalkyl) or aryl diradical which may contain cyano, nitro, halo,alkyl sulfide, dialkylamino, substituted silane, alkoxy, and aryloxymoieties, and other substituted species of any of the foregoing; andwherein d is 0 to about 12, n is 0 to about 6, m is 3 to about 5, p is 1to about 6, and q is 0 to about
 4. 5. A surface-active polycarbodiimideof claim 4 wherein the monodisperse, branched polycarbodiimide has thegeneralized structure: ##STR6## wherein: R¹, R², R³ and R⁴ may be thesame or different and represent organic residues which do notsubstantially interfere with the multifunctional carbodiimide for itsintended purpose; and D is an organic residue; and r, s, t, x and y are1 to about
 6. 6. A surface-active polycarbodiimide of claim 4 whereinthe monodisperse, branched polycarbodiimide has the generalizedstructure: ##STR7## wherein: R¹, R², and R⁴ may be the same or differentand represent alkyl groups having 1 to about 12 carbon atoms; R⁵ and R⁶may be the same or different and represent hydrogen, alkyl (includingcycloalkyl), aryl, aralkyl, alkaryl, heterocyclic, cyano, nitro, halo,alkyl sulfide, dialkylaminoalkyl, silane, alkoxy, and aryloxy groups,and substituted species of any of the foregoing; Z is the residue of acompound adapted to function as a site for branching; and wherein a, b,and c are 0 to about
 12. 7. A surface-active polycarbodiimide of claim 4wherein the monodisperse, branched polycarbodiimide is1,3,6-tri-(N-isopropyl-N'-methylene carbodiimide) hexane.
 8. Asurface-active polycarbodiimide of claim 4 wherein the monodisperse,branched polycarbodiimide is 1,3,6-tri-(N-cyclohexyl-N'-methylenecarbodiimide) hexane.
 9. A surface-active polycarbodiimide of claim 4wherein the monodisperse, branched polycarbodiimide is1,3,6-tri-(N-n-butyl-N'-methylene carbodiimide) hexane.
 10. Asurface-active polycarbodiimide of claim 1 wherein R is a residue of apolydisperse, linear polycarbodiimide.
 11. A surface-activepolycarbodiimide of claim 10 wherein R is a residue of a polyfunctionalPCD1 derived from the reaction of mono-, di-, and tri-cycloaliphatic orsaturated aliphatic isocyanates wherein the cycloaliphatic moietiescontain from 5 to about 7 carbons and can be substituted with alkylhaving 1 to about 6 carbons, and oxygen, and the saturated aliphaticmoieties contain from 1 to about 18 carbons, wherein the mono- andtriisocyanates are optional.